Understanding Nuclear Fission and Fusion: Processes, Energy Release, and Comparison, Study notes of Nuclear Engineering

Download Understanding Nuclear Fission and Fusion: Processes, Energy Release, and Comparison and more Study notes Nuclear Engineering in PDF only on Docsity!

NUCLEAR

FISSION AND

FUSSION

Nuclear Fission

Fundamentals Of Nuclear

Fission

 The fission process may be best understood

through a consideration of the structure and

stability of nuclear matter.

 There is always a difference between actual mass

of a nucleus and the mass number, this is known

as mass defect and is a measure of total binding

energy.

 The highest binding energy and thus the most

stable state occurs at mass number 56.

 (^) Thus a high mass number tries to split itself in achieving this mass number and releasing a high amount of energy. Fig. Average Binding Energy per Nucleus

Fission Process

 Certain nuclei, like uranium-235, uranium-

233 and plutonium-239, can sustain a fission chain

reaction.

 A nuclear chain reaction occurs when one single

nuclear reaction causes an average of one or

more subsequent nuclear reactions, thus leading to

the possibility of a self-propagating series of these

reactions. The “one or more” is the key parameter

of reactor physics. To raise or lower the power, the

amount of reactions must be changed (using

the control rods) so that the number of neutrons

present (and hence the rate of power generation) is

either reduced or increased.

Fig. Nuclear Chain Fission Reaction

What Is Nuclear Fusion?

 In nuclear physics, nuclear fusion is a reaction in

which two or more atomic nuclei are combined to

form one or more different atomic nuclei and

subatomic particles (neutrons or protons). The

difference in mass between the reactants and

products is manifested as either the release or

absorption of energy.

 Fusion reactions are of two basic types:

 (^) Those that preserve the number of protons and neutrons. (most important for practical energy production) D + T → He + n  (^) Those that involve a conversion between protons and neutrons. (Crucial to the initiation of star burning) H + H → D + β

• ν

Energy Released In Fusion Reaction

 Energy is released in a nuclear reaction if the total

mass of the resultant particles is less than the mass

of the initial reactants.

 In practical energy generation we use the D-T

reaction for two reasons:

I. The rate of reactions between deuterium and tritium is much higher than that between protons II. The net energy release from the D-T reaction is 40 times greater than that from the H-H reaction.

 One ton of deuterium has the energy equivalent of

approximately 29 billion tons of coal.

Comparison Between Nuclear Fission And Fusion

Nuclear Fission Nuclear fusion Definition Fission is the splitting of a large atom into two or more smaller ones. Fusion is the fusing of two or more lighter atoms into a larger one. Natural occurrence of the process Fission reaction does not normally occur in nature. Fusion occurs in stars, such as the sun. By-products of the reaction Fission produces many highly radioactive particles. Few radioactive particles are produced by fusion reaction, but if a fission "trigger" is used, radioactive particles will result from that. Conditions Critical mass of the substance and high-speed neutrons are required. High density, high temperature environment is required. Energy Requirement Takes little energy to split two atoms in a fission reaction. Extremely high energy is required to bring two or more protons close enough that nuclear forces overcome their electrostatic repulsion. Energy Released The energy released by fission is a million times greater than that released in chemical reactions, but lower than the energy released by nuclear fusion. The energy released by fusion is three to four times greater than the energy released by fission. Nuclear weapon One class of nuclear weapon is a fission bomb, also known as an atomic bomb or atom bomb. One class of nuclear weapon is the hydrogen bomb, which uses a fission reaction to "trigger" a fusion reaction. Energy production Fission is used in nuclear power plants. Fusion is an experimental technology for producing power. Fuel Uranium is the primary fuel used in power plants. Hydrogen isotopes (Deuterium and Tritium) are the primary fuel used in experimental fusion power plants.

Bibliography

 (^) Ellis P. Steinberg (July 06, 2018) , Nuclear fission. Retrieved from https://www.britannica.com/science/nuclear-fission/  (^) Nuclear power. Retrieved from https://www.nuclear-power.net/nuclear-power/fission/  (^) Nuclear Fission. Retrieved from https://en.wikipedia.org/wiki/Nuclear_fission/  (^) Nuclear Fusion. Retrieved from https://en.wikipedia.org/wiki/Nuclear_fusion/  (^) Robert W. Conn (July 06, 2018) , Nuclear fusion. Retrieved from https://www.britannica.com/science/nuclear-fusion/  (^) Uunderstanding of Nuclear Fusion. Retrieved from http://fusionforenergy.europa.eu/understandingfusion/  (^) A Fusion Reactor. Retrieved from https://www.ems.psu.edu/~radovic/Chapter14.pdf/  (^) Comparison Between Nuclear Fission And Fusion. Retrieved from https://www.diffen.com/difference/Nuclear_Fission_vs_Nuclear_Fusion/